CHICAGO — For the first time in a decade, an experimental drug has extended the life of patients with advanced lung cancer who relapsed after standard chemotherapy.

But the benefit in the study was so small — six extra weeks, on average — that it is raising fresh questions about the value of some costly new cancer medicines.

Eli Lilly and Co.'s drug Cyramza (sih-RAM-zuh) was tested in more than 1,200 patients. It is sold now for stomach cancer and costs $6,000 per infusion.

The study was discussed Saturday at a cancer conference in Chicago where doctors also reported progress with new drugs against relapsed ovarian cancer and chronic lymphocytic leukemia, the most common type of leukemia in adults.